A Low-noise amplifier is typically the first active electronic component to process a radio-frequency signal received by a wireless communication device, such as a mobile telephone or two-way radio. Any noise and distortion introduced at this early stage of signal processing is likely to propagate through the receiving equipment, so it is important to select a low-noise amplifier with a low noise figure (NF) and high linearity.
There are several known design constraints that make it difficult to achieve low noise figure and high linearity while also satisfying requirements for input and output impedance matching, reverse isolation, stability, and low current consumption. These constraints are particularly difficult to satisfy where a receiver is required to have the capability of monitoring more than one wireless channel at a time, as in the case of a dual-watch radio. In such cases, it is possible to passively split the input signal and to amplify the split signal with two separate low-noise amplifiers. Alternatively, it is possible to use a single low-noise amplifier and to passively split the outputs. Both of these solutions require additional current consumption due to the need to increase gain to account for passive loss at the splitter.
Accordingly, there is a need for a switchable multi-output low-noise amplifier with distortion cancellation.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.